About

Ram Seshadri is a Distinguished Professor in the Department of Chemistry & Biochemistry and the Materials Department at the University of California, Santa Barbara. He specializes in Inorganic Materials Chemistry and Functional Inorganic Materials. Ram received his PhD in Solid State Chemistry from the Indian Institute of Science in 1995, working with Professor C. N. R. Rao FRS on carbon nanostructures. Following postdoctoral fellowships in Caen, France, with Professor Bernard Raveau, and in Mainz, Germany, with Professor Wolfgang Tremel, he returned to Bangalore as an Assistant Professor at the Indian Institute of Science. In 2002, he moved to UC Santa Barbara, where he has been a faculty member since 2008. His research group aims to develop a fundamental understanding of functional materials that impact everyday life, focusing on the compositional tuning of properties of extended solids through solid solution. His work includes preparing and characterizing new materials, understanding the theory behind functional materials, and developing tools to probe them. Ram serves on the Editorial Committee of the Annual Reviews of Materials Research and is an Associate Editor of the ACS Journal Chemistry of Materials.

Research topics

• Physics
• Computer Science
• Materials science
• Artificial Intelligence
• Machine Learning
• Organic chemistry
• Chemistry
• Optoelectronics
• Optics
• Inorganic chemistry
• Condensed matter physics
• Crystallography
• Composite material
• Nanotechnology
• Quantum mechanics
• Physical chemistry
• Algorithm
• Photochemistry

Selected publications

• Direct Microwave Pyrolysis of Cellulose to Hard Carbon Anodes for Sodium-Ion Batteries

  Chemistry of Materials · 2026-01-17

  articleSenior authorCorresponding

  Hard carbons are the leading anode material in Na-ion batteries due to their considerable ability to store Na, and the ease with which they can be produced from inexpensive precursors such as cellulose through pyrolysis in inert atmospheres. Here, we report a rapid one-step conversion of cellulose to hard carbons in under 15 min in a modified domestic microwave oven. This is in contrast to more conventional furnace-based pyrolysis which can take several hours. From optical pyrometry, we find that under different microwave power conditions, the hard carbons can be tunably formed at temperatures between 900 to 1250 °C under the conditions employed. The hard carbons produced here have been characterized by Raman spectroscopy, wide and small-angle X-ray diffraction, porosimetry, X-ray photoelectron spectroscopy, and X-ray pair distribution function analysis. As a function of increasing microwave power, the carbons are found to exhibit comparable local structure but enhanced crystallinity and evidence of an increased proportion of closed pores. The formation of closed pores appears to directly contribute to significant gains in Na storage capacity throughout the plateau region during electrochemical cycling. These results demonstrate a convenient and scalable strategy for rapidly producing hard carbons with tunable porosity.

  PublisherDOI

• Enhanced Sodium Dynamics in Biphasic NaSICON Solid Electrolytes

  Chemistry of Materials · 2026-02-23

  article

  NaSICONs, or sodium superionic conductors, are promising solid electrolyte materials for Na-based all-solid-state and aqueous redox-flow battery applications. Here, the composition Na3.4Zr2Si2.4P0.6O12 has been prepared through solution-assisted microwave processing and densification through rapid induction hot pressing. The samples display remarkably high total ionic conductivities between 7 and 9 mS cm–1, competitive with liquid electrolytes. A combination of synchrotron X-ray and neutron diffraction, electrochemical impedance spectroscopy, and variable-temperature solid-state nuclear magnetic resonance studies reveals rapid Na-ion transport through the rigid skeletal framework of this solid ion conductor. Variable-temperature synchrotron X-ray diffraction reveals structural phase separation in this composition on cooling at temperatures close to 430 K with the samples at room temperature displaying a mix of monoclinic C2/c and rhombohedral R3̅c components that appear to collectively contribute to the high conductivity. The observation of very high ionic conductivity in a region of compositional space that is associated with structural instability is proposed as a design principle for superionic conduction.

  PublisherDOI

• Metallic Oxides and the Overlooked Role of Bandwidth

  Chemistry of Materials · 2026-01-30 · 2 citations

  articleOpen accessSenior author

  Oxides exhibiting metallic conduction are crucial for various applications, including fuel cells, battery electrodes, resistive and magnetoresistive materials, electrocatalysts, transparent conductors, and high-temperature superconductors. Oxides that approach metallicity also play significant roles in switching applications, where the metal-insulator transition phenomenon is utilized across a range of technologies. This perspective, motivated by the question of when oxides are metallic, employs electronic structure calculations on metallic oxides to identify typical features in the electronic structure that promote metallic behavior. The critical factor of the bandwidth of the electronic energy bands near the Fermi energy is emphasized since it has been somewhat overlooked in the literature. For example, bandwidth considerations would suggest that the recently proposed phosphate "LK-99" would never be a suitable target for superconductivity. By relating the crystal structure and electronic band features obtained through density functional theory calculations, we present the general heuristic that crystals with conduction bands narrower than 1 eV (as obtained from routine electronic structure methods) are unlikely to be metallic. We further examine the origins of narrow or flat bands to distinguish between structural properties that are conducive or detrimental to physical behavior like superconductivity. This survey of representative oxide metals highlights the essential chemical and structural ingredients that contribute to extended covalent interactions and ultimately wide electronic bands. A key takeaway is that oxyanion compounds such as borates, carbonates, silicates, sulfates, nitrates, and phosphates are unlikely to exhibit metallic conduction at ambient pressure. While the focus here is on oxides, the general findings should apply across various material families, extending to conducting organic crystals, conducting polymers, and hybrid and framework materials.

  PublisherOA PDFDOI

• Two-step spin-coating of vacancy-ordered double perovskites enables growth of thin films for electronic devices

  Journal of Materials Chemistry C · 2025-01-01 · 1 citations

  articleOpen access

  A two-step process was developed to spin-coat thin films of the vacancy-ordered double perovskite, Cs 2 TeX 6 . These films enabled characterization of the electronic transport properties of Cs 2 TeBr 6 .

  PublisherOA PDFDOI

• Metallic Oxides and the Overlooked Role of Bandwidth

  ArXiv.org · 2025-10-01

  preprintOpen accessSenior author

  Oxides exhibiting metallic conduction are crucial for various applications, including fuel cells, battery electrodes, resistive and magnetoresistive materials, electrocatalysts, transparent conductors, and high-temperature superconductors. Oxides that approach metallicity also play significant roles in switching applications, where the metal-insulator transition phenomenon is utilized across a range of technologies. This perspective, motivated by the question of when oxides are metallic, employs electronic structure calculations on metallic oxides to identify the typical feature in the electronic structures that promote metallic behavior. The critical factor of the bandwidth of the electronic energy bands near the Fermi energy is emphasized since it has been somewhat overlooked in the literature. For example, bandwidth considerations would suggest that the recently proposed phosphate "LK-99" would never be a suitable target for superconductivity. From the analysis performed here, we learn that if the width of the conduction band as obtained from density functional theory-based electronic structure calculations is less than 1 eV, then the likelihood of obtaining a metallic compound is vanishingly small. This survey of representative oxide metals highlights the essential elements of extended covalency that lead to wide bands. A key takeaway is that oxyanion compounds such as borates, carbonates, silicates, sulfates, nitrates, and phosphates are unlikely to exhibit metallic conduction at ambient pressure. While the focus here is on oxides, the general findings should apply across various material families, extending to organic crystals, polymers, and framework materials.

  PublisherOA PDFDOI

• Metallicity, Atomic Disorder, and Li-Ion Storage in Fast-Charging Anodes

  Journal of the American Chemical Society · 2025-09-02

  articleOpen accessSenior authorCorresponding

  Oxides of Nb with Wadsley-Roth shear structures comprise a family of stable, high-rate anode materials for Li-ion batteries. A particular pair of them offers the unusual opportunity to test how important metallic conduction of the starting electrode is for electrode performance. The selected pair of compounds with similar 4 × 3 Wadsley-Roth block structures are insulating Ti2Nb10O29 and metallic Nb12O29. A combination of diffraction, electrochemistry, magnetic measurements, and entropic potential measurements is employed to establish key findings for these two anode materials. We find that starting with a metallic oxide is not especially advantageous over a comparable material that readily transitions into a metallic state upon lithiation. Second, the rate performance appears to be dictated by ion mobility, and atomic Ti/Nb disorder in Ti2Nb10O29 contributes to improved capacity retention at high rates by suppressing Li-ion ordering. However, subtle details in the nature of redox processes make Nb12O29 a slightly better electrode material for long-term cycling at slower rates.

  PublisherDOI

• Selective Phase Stabilization in Microwave-Prepared Nasicon Solid Electrolytes through Potassium Ion Exchange

  ECS Meeting Abstracts · 2025-07-11

  article

  Sodium solid-state batteries offer a promising alternative to lithium-ion batteries by leveraging the abundance and widespread availability of sodium paired with the increased safety and high energy density of ceramic electrolytes. The solid electrolyte material NaSICON is generally prepared through solid-state reaction, often paired with co-precipitation or sol-gel methods to ensure homogeneous mixing of precursors. Traditional solid-state reactions consist of mixing solid precursors and pelletizing reagents, followed by heat treatment for several hours in a furnace. Since the energy required for heat treatment drives the cost of ceramic oxide membranes, 1 developing low energy intensity synthesis methods is necessary to commercialize solid electrolytes. In this study, NaSICON is prepared through microwave-assisted solid-state synthesis and densified through rapid induction hot pressing. Microwave-assisted solid-state reaction pathways can reach high temperatures of up to 1500°C in a short period of time 2 through direct heating of the precursor mixture, rather than heating the complete interior of the device as in a furnace. This allows for rapid reaction times and energy efficiency compared to conventional furnace heating. NaSICON is a solid solution series with the composition Na 1+x Zr 2 (SiO 4 ) x (PO 4 ) 3-x . The composition Na 3.4 Zr 2 Si 2.4 P 0.6 O 12 has been previously shown to exhibit the maximum conductivity above 5 mS cm -1 . 3 While the end members NaZr 2 (PO 4 ) 3 and Na 4 Zr 2 (SiO 4 ) 3 crystallize in the rhombohedral R -3 c (no. 167) space group, Na 3.4 Zr 2 Si 2.4 P 0.6 O 12 crystallizes in a mixture of the monoclinic C 2/ c (no. 15) and rhombohedral R -3 c (no. 167) space groups, with monoclinic as the primary phase. In this work, synthesized NaSICON is immersed in potassium chloride solution resulting in an ion exchange between sodium and the larger potassium ion, which selectively stabilizes the rhombohedral phase. NaSICON (Na 3.4 Zr 2 Si 2.4 P 0.6 O 12 ) samples were synthesized through co-precipitation followed by ball milling, then reacted in a domestic microwave oven using activated charcoal as a room temperature microwave susceptor. The crystalline NaSICON was then densified through rapid induction hot pressing and characterized through synchrotron x-ray diffraction (SXRD) at Diamond Light Source and variable temperature electrochemical impedance spectroscopy. The densified samples were placed into potassium chloride solution for varying amounts of time. Using the combination of microwave synthesis and rapid induction hot pressing, densified samples with high conductivities of 6-7 mS cm -1 were achieved. Arrhenius analysis of variable temperature electrochemical impedance data gives a bulk activation energy of 0.25 eV with a total activation energy of 0.29 eV. Rietveld refinement of SXRD data shows a mixture of monoclinic and rhombohedral NaSICON structures with minor secondary phases of monoclinic zirconia and β-quartz (SiO 2 ) (Fig. 1). Synthesized NaSICON immersed in an aqueous KCl solution at room temperature has been found to undergo ion exchange between Na and K, resulting in a pure rhombohedral crystal phase with a 4% increase in the c lattice parameter due to the increased size of potassium. Room temperature stabilization of the rhombohedral phase, which is generally stable above 200°C, 3 has potential implications on conductivity due to an increase in the size of the sodium diffusion channel within the crystal structure. References (1) Schnell, J.; Tietz, F.; Singer, C.; Hofer, A.; Billot, N.; Reinhart, G. Prospects of Production Technologies and Manufacturing Costs of Oxide-Based All-Solid-State Lithium Batteries. Energy & Environmental Science 2019 , 12 (6), 1818–1833. (2) Levin, E. E.; Grebenkemper, J. H.; Pollock, T. M.; Seshadri, R. Protocols for High Temperature Assisted-Microwave Preparation of Inorganic Compounds. Chem. Mater. 2019 , 31 (18), 7151–7159. (3) Ma, Q.; Tsai, C.-L.; Wei, X.-K.; Heggen, M.; Tietz, F.; Irvine, J. T. S. Room Temperature Demonstration of a Sodium Superionic Conductor with Grain Conductivity in Excess of 0.01 S cm −1 and Its Primary Applications in Symmetric Battery Cells. J. Mater. Chem. A 2019 , 7 (13), 7766–7776. Fig. 1 Rietveld refinement of synchrotron x-ray diffraction data for microwave-prepared NaSICON shows a mixture of monoclinic and rhombohedral NaSICON structures with minor secondary phases of monoclinic zirconia and β-quartz (SiO 2 ). Figure 1

  PublisherDOI

• Pyrolyzed “Black Mass” Feedstocks and Their Synthetic Proxies Relevant to Li-Ion Battery Recycling

  ACS Omega · 2025-06-10 · 7 citations

  articleOpen accessSenior authorCorresponding

  Lithium-ion battery (LIB) recycling aims to recover valuable materials present within end-of-life electrochemical cells. Industrial recycling processes produce “black mass” from recycling feedstock from which desirable materials can be recollected. Spent cells first undergo mechanical shredding and sieving, and organic components are removed by thermal treatment (pyrolysis) before hydrometallurgical processing is employed to recover the constituent elements. Black mass may contain a range of reaction products, formed at high temperature during pyrolysis, due to the compositionally complex and inhomogeneous nature of recycling feedstock. These products, however, may have different elemental compositions, ratios, and structures, making efficient hydrometallurgical recovery difficult. Here, we present three distinct, industrially sourced black mass samples containing Li(NixMnyCoz)O2 (x + y + z = 1) positive electrodes of varying composition. We employ a suite of structural and compositional characterization techniques, including synchrotron X-ray and neutron powder diffraction and element specific analysis (X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy, energy dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectroscopy), to identify phases formed during commercial treatment of recycling feedstocks and how their relative quantities are affected by process order. Additionally, we also present results of studies on simpler model systems to better identify minor phases present within the complex recycling feedstocks and to direct the efficient recovery of valuable components.

  PublisherDOI

• Spin Chains with Highly Quantum Character through Strong Covalency in Ca₃CrN₃

  Journal of the American Chemical Society · 2025-01-21

  article

  The insulating transition metal nitride Ca3CrN3 consists of sheets of triangular [CrN3]6– units with C2v symmetry that are connected via quasi-1D zigzag chains. Due to strong covalency between Cr and N, Cr3+ ions are unusually low-spin, and S = 1/2. Magnetic susceptibility measurements reveal dominant quasi-1D spin correlations with very large nearest-neighbor antiferromagnetic exchange J = 340 K and yet no sign of magnetic order down to T = 0.1 K. Density functional theory calculations are used to model the local electronic structure and the magnetic interactions, supporting the low-spin assignment of Cr3+ that is driven by strong π donation from the nitride ligands. The surprising failure of interchain exchange to drive long-range magnetic order is accounted for by the complex connectivity of the spin chain pairs that further frustrates order. Our combined results establish Ca3CrN3 as a nearly ideal manifestation of a quantum spin chain whose dynamics remain unquenched down to extraordinarily low temperatures despite strong near-neighbor exchange coupling.

  PublisherDOI

• Tuning optical properties and local lone-pair off-centering in “hollow” FA _{1− <i>x</i>} { <i>en</i> } _<i>x</i> Pb _{<i>η</i> − <i>y</i>} Sn _<i>y</i> Br ₃ perovskites

  Chemical Science · 2025-10-31

  articleOpen access

  hollow perovskites. These compounds have wide ranging optical gaps from 1.9 eV (deep red) to 2.6 eV (light yellow), combining the anomalous bandgap red-shifting of Pb/Sn mixing with the blue-shifting effects of the organic substitution. Average and local structural studies employing single crystal X-ray diffraction and total X-ray scattering pair distribution function analyses respectively suggest strong incoherent off-centering distortions that are locally correlated with Sn concentration. The inclusion of ethylenediammonium dications appears to regulate metal off-centering, opening new opportunities of research into this phenomenon.

  PublisherOA PDFDOI

Recent grants

• Materials Research Science and Engineering Center at UCSB

  NSF · $24.0M · 2017–2024

• Magnetostructural Coupling in Itinerant Magnets

  NSF · $450k · 2017–2020

• Spin and positional disorder in complex oxides

  NSF · $425k · 2011–2014

• Shared Facilities Operations Workshop 2018

  NSF · $72k · 2018–2020

• CAREER: Ferromagnetic Half Metals by Design

  NSF · $482k · 2005–2011

Frequent coauthors

• Anthony K. Cheetham

  University of California, Santa Barbara

  182 shared

• Stephen D. Wilson

  University of California, Santa Barbara

  102 shared

• Mercouri G. Kanatzidis

  Northwestern University

  93 shared

• Guang Wu

  University of California, Santa Barbara

  72 shared

• Lingling Mao

  Southern University of Science and Technology

  64 shared

• Pratap Vishnoi

  Jawaharlal Nehru Centre for Advanced Scientific Research

  63 shared

• Michael L. Chabinyc

  University of California, Santa Barbara

  58 shared

• C. N. R. Rao

  Jawaharlal Nehru Centre for Advanced Scientific Research

  57 shared

Education

• PhD, Solid State and Structural Chemistry Unit

  Indian Institute of Science